Exchange 2000 RC2 Install SP2

In my test enviroment I have AD running.Installed exchange 2000 few weeks ago.ran Forestprep,domainprep prior.exchange 2000 is running on new redundant DC.Ran most diagnostics namely dcdiag,netdiag,ntfrsutil,repadmin.All changes have been replicatedbetween DC’s.DC’s are on one Site namely default created Site.the problem is when I downloaded SP2,Extracted and ran update,I consistently get the message the schema is not up to date and i need to run forestprep or domainprep.I removed the heuristics value through adsiedit,ran forestprep and domainprep and have been unable to apply the SP2.Repadmin shows schema is up to date.
Any thoughts will be welcome
Thanx